1. The Field of the Invention
This invention relates to a novel plant fertilizer composition and to a method of fertilizing plants growing in soil by applying thereto an effective amount of said composition. More particularly, the present invention relates to a novel plant fertilizer composition which comprises a particulate carbonaceous material containing releasable plant nutrients and an agent for releasing said plant nutrients in a form that the plants are capable of utilizing.
2. The Prior Art
Heretofore mixtures of carbonaceous materials such as coal and various additives have been used to fertilize growing plants and/or to condition the soil in which the plants are grown. U.S. Pat. No. 128,578 discloses a mixture of coal and iron sulfate while U.S. Pat. No. 143,213 discloses a mixture of coal and lime for such purposes.
Fertilizer compositions produced from coal and various additives have also been disclosed in U.S. Pat. Nos. 620,443 and 445,255 wherein the additive is phosphate rock and a reaction is effected by the addition thereto of sulfuric acid. In U.S. Pat. No. 1,196,889 a mixture of coal and natural salt water are subjected to a mild heat treatment to produce a fertilizer. A mixture of rock phosphate, lime, ammonium sulfate, salt and coal, in U.S. Pat. No. 2,059,600, is roasted at a temperature of 600.degree.-800.degree. F. to produce a fertilizer. U.S. Pat. No. 4,013,440 discloses extracting nitrogeous material from coal by treatment with urea to which is then added an oxidizing agent and an alkali. A more recent development in coal-based fertilizers is disclosed in U.S. Pat. No. 4,067,712 wherein lignite is treated with the reaction product of alkali metal silicate and a source of calcium ions and magnesium ions. A somewhat similar disclosure appears in U.S. Pat. No. 4,067,714.